Method for detecting a hopper insertion state for a bag-filling packaging machine

ABSTRACT

A method for detecting a hopper insertion state for a bag-filling packaging machine using photoelectric sensors  7  provided at an item supply step position. The photoelectric sensors  7  detect deformation of the bag mouth that occurs when the hopper  4  is inserted into the bag mouth, and a decision whether the insertion status of the hopper  4  in the bag mouth is good or bad is made based on the detection result of the photoelectric sensors  7 . If the tip end of the descending hopper  4  catches the bag mouth or presses the bag mouth and folds it, the bag face is moved away from the detection part  9  (light passage route) of the sensors  7 , so that light from the light-emitting part of the sensors  7  reaches a reflecting mirror  6  and reflected, and the reflected light is detected by the light-receiving part of the sensors  7.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a hopper detecting method in abag-filling packaging machine that opens a bag mouth of a supplied bag,inserts a hopper into the bag mouth, loads the items to be packed intothe bag via the hopper, and then withdraws the hopper from the bag mouthafter the loading; and more particularly, the present invention relatesto a method for detecting whether or not the hopper is inserted into thebag mouth normally.

2. Description of the Related Art

A bag-filling packaging machine generally opens a bag mouth, inserts ahopper end into the bag mouth, and loads the items to be packed into thebag via the hopper (see Japanese Patent Nos. 2981952, 2745203 and3582681, Japanese Patent Application Laid-Open (Kokai) No. 2004-67224,and Japanese Patent Application Laid-Open (Kokai) No. 2005-29175).

Usually, the diameter of the opening of the hopper's insertion end isset to be large, with the maximum limit being so that it can be insertedinto the bag mouth, thus allowing the items to be packed to through thehopper reliably and swiftly. Therefore, if the bag mouth is not openedfully or if the opening shape of the bag mouth is deformed from thenormal shape, the hopper's insertion opening end catches the edge of thebag mouth end when the hopper is inserted, so that part of the insertionopening end may be exposed outside the bag or be blocked by the foldedbag mouth. As a result, various loading errors may occur; in otherwords, the items to be packed may spill outside the bag, passage of theitems to be packed may be interfered with and the items to be packed maynot be loaded into the bag, or loading of the items to be packed may notbe completed within the predetermined time.

The conventional way of keeping this sort of problem from occurring isto provide an opening guide device that has a plurality of rod-shaped orplate-shaped opening claws at a predetermined position on a bag-fillingpackaging machine. The opening claws are inserted inside the opened bag,the opening shape of the bag mouth is kept in a predetermined shape, andthen the hopper is inserted into bag mouth (see Japanese Patent No.2981952). However, there are problems. Providing the opening guidedevice makes the structure of the bag-filling packaging machinecomplicated and increases the cost. In addition, the bag-filling stepsin the bag-filling packaging machine increases, reducing productivity.

In addition, in the case of the ordinary rotary-type bag-fillingpackaging machine disclosed in Japanese Patent No. 2981952, only onehopper is disposed at a predetermined position (in the case of aso-called W-type machine, in which two bags are simultaneously filled,there is one hopper corresponding to each bag, for a total of twohoppers). But in the case of a bag-filling packaging machine in which aplurality of hoppers are provided (corresponding to each gripper pairrespectively) on a rotary table, as disclosed in, for example, JapanesePatent Application Laid-Open (Kokai) No. 2004-67224, providing openingguide devices is very difficult in terms of space and structure.

On the other hand, assuming that loading errors will occur, it isconventional practice to detect items to be packed that are loaded intoa bag with a proximity sensors or vibrations sensors, thus determiningwhether or not a loading error has occurred (see Japanese PatentApplication Publication (Kokoku) No. H3-56973 and Japanese Patent No.3436406). However, if a very small quantity of items to be packed spillsoutside the bag, making that decision is very difficult.

Also, though a sensor for detecting items to be packed that fill theinterior of a bag is used conventionally (see Japanese Patent No.2745203), this method cannot detect items to be packed that spilloutside the bag, and loading errors are overlooked.

When items to be packed are loaded into a bag via a hopper in abag-filling packaging machine, nearly all of the loading errors occurwhen the insertion end of the hopper is not inserted properly (orcorrectly) into the bag mouth. To put it another way, if it werepossible to detect whether or not the insertion end of the hopper wasinserted normally into the bag mouth, then it would be possible todetect the occurrence of loading errors and in addition to prevent theoccurrence of loading errors.

BRIEF SUMMARY OF THE INVENTION

Accordingly, the object of the present invention is to provide a methodfor detecting whether or not the insertion end of a hopper is insertedinto a bag mouth in a normal or correct fashion.

Generally, when inserting the hopper, if its insertion end catches onthe bag mouth edge and is not inserted normally into the bag mouth, thebag mouth is pressed by the insertion opening end of the hopper anddeforms (often it is folded inward). Also, if the bag-filling packagingmachine is the type that holds both edges of the bag with grippers andsupports it with the bag hanging down (a so-called vertical-typepackaging machine), the deformed bag mouth partially blocks theinsertion opening end of the hopper and interferes with passage of theitems to be packed, and items to be packed that remain inside the hopperfall when the hopper is withdrawn from the bag mouth. Therefore, if itwere possible to detect deformation of the bag mouth when the hopper isinserted into the bag mouth and/or to detect the items to be packedfalling from the hopper when the hopper is withdrawn from the bag mouth,then it is possible to detect whether or not the insertion end of thehopper was normally inserted inside the bag mouth. The present inventionis based on this knowledge.

Accordingly, the above object is accomplished by unique steps of thepresent invention for detecting a hopper insertion state in abag-filling packaging machine that opens a bag mouth of a supplied bag,inserts a hopper in the bag mouth of the supplied bag, loads the itemsto be packed into the supplied bag via the hopper, and then withdrawsthe hopper from the bag mouth; and in the present invention, sensors fordetecting deformation of the bag mouth based on the insertion operationof the hopper (bag mouth detecting sensors) are provided in thebag-filling packaging machine; and deformation of the bag mouth duringthe insertion operation of the hopper is detected by the bag mouthdetecting sensors, and whether the hopper insertion state in the bagmouth is good or bad or acceptable or not is determined based on thedetection result of the bag mouth detecting sensors.

This method of the present invention is applicable to the type ofbag-filling packaging machine that holds both edges of a supplied bagwith grippers and supports it with the bag hanging down while variouspackaging operations are performed (the so-called vertical-typepackaging machine disclosed in, for instance, the above-describedJapanese Patent Nos. 2981952, 2745203 and 3436406, Japanese PatentApplication Laid-Open (Kokai) No. 2004-67224 and Japanese PatentApplication Publication (Kokoku) No. H3-56973) and also to the type ofbag-filling packaging machine that holds the bag mouth using grippers,suction cups, etc. with the bag in a prone state while various packagingoperations are performed (the so-called lateral-type packaging machinedisclosed in, for instance, the above-described Japanese PatentApplication Laid-Open (Kokai) No. 2005-29175 and Japanese Patent No.3582681).

In the case of vertical-type packaging machines, the method of thepresent invention is generally applicable to vertical-type packagingmachines, such as a rotary table type bag-filling packaging machine inwhich a plurality of gripper pairs are provided on the periphery of arotating table that is rotated continuously or intermittently, anendless track type bag-filling packaging machine in which a plurality ofgripper pairs are provided on a chain, etc. that moves continuously orintermittently along a ring-shaped track, and in addition to a linearmovement type bag-filling packaging machine in which one gripper pair ora plurality thereof undergoes reciprocating motion in a straight line,etc.

In addition, the method of the present invention is not just applicableto a bag-filling packaging machine in which a bag mouth is sealed andthen the bag is discharged to the outside of the machine in a singlepackaging operation, and it can also be applied to a bag-fillingpackaging machine in which the bag is discharged to outside the machinewithout sealing all the bag mouths or without sealing the bag mouthcompletely (for example, when the bag is sent to a vacuum packagingmachine via a transfer device).

Also, the method for detecting a hopper insertion state of the presentinvention is applicable only to a vertical-type packaging machine. Morespecifically, the present invention provides a hopper insertion statedetecting method for a bag-filling packaging machine that holds bothedges of a supplied bag with grippers and supports the bag hanging down,opens the bag mouth of the supplied bag, inserts a hopper in the bagmouth, loads the items to be packed into the bag via the hopper, andthen withdraws the hopper from the bag mouth; and in the presentinvention, sensors for detecting items to be packed falling from thehopper when the hopper is withdrawn from the bag mouth (falling itemsdetecting sensors) are provided in the bag-filling packaging machine;and the falling items detecting sensors detects items falling from thehopper when the hopper is withdrawn from the bag mouth, and whether thehopper insertion state in the bag mouth is good or bad or acceptable ornot is determined based on the detection result of the falling itemsdetecting sensors. This method can be used in conjunction with thepreviously described method for detecting a hopper insertion state thatuses the bag mouth detecting sensors (for detecting deformation of thebag mouth).

Furthermore, the method of the present inventive is particularlysuitable to a bag-filling packaging machine of the type in which aplurality of grippers for holding both the left and right edges (or bothside edges) of a bag so that the bag hangs down are disposed atequidistant separation on the periphery of an intermittently rotatingtable, and a hopper that is raised and lowered at a predetermined timingis disposed on the table to correspond to each respective gripper pair;and various packaging means such as a bag supply device, a bag mouthopening device, an item supply device, a sealing device, etc. aredisposed on the periphery of the table, so that various packagingoperations such as supplying of a bag, opening of the bag mouth,inserting of the hopper into the bag mouth, loading of the items to bepacked into the bag, withdrawing of the hopper from the bag mouth,sealing of the bag mouth, etc. are performed when the table is rotatedonce.

If the insertion end opening of the hopper catches on the bag mouth edgewhen the hopper is inserted into the bag mouth of the supplied bag, thebag mouth of the supplied bag is pressed by the opening end of thehopper and deforms. The present invention detects the presence orabsence of this deformation; and based on the detection result of thesensors, a control device determines whether or not the hopper wasinserted normally inside the bag mouth. Thus, detection and decision ofthe hopper insertion state can be done easily.

In the method of the present invention, if it is determined that thehopper is not inserted into the bag mouth normally, it is possible tostop injecting the items to be packed into the relevant hopper in, forexample, the loading step based on the decision result. It is alsopossible to halt the operation of the packaging means (for example, aliquid loading device, bag mouth sealing device, device to transfer to avacuum packaging machine, etc.) at steps following the relevant bag, orto discharge only the relevant bag at a discharge position differentfrom the usual discharge position, or to halt the entire packagingdevice.

On the other hand, in a vertical-type packaging machine, when theinsertion end opening of the hopper catches on the bag mouth edge whenthe hopper is inserted into the bag mouth of the supplied bag, the bagmouth is pressed by the hopper's opening end and deformed; and if itdeforms inward, the deformed bag mouth partially blocks the insertionopening end of the hopper and interferes with passage of the items to bepacked, and the items to be packed remain inside the hopper or cannotpass through it within the expected time, and the items to be packedthat remain inside the hopper fall when the hopper is withdrawn from thebag mouth.

Thus, in another method of the present invention, the presence orabsence of items to be packed is detected when they fall from the hopperupon the withdrawal of the hopper from the bag mouth, and a controldevice determines whether or not the hopper was inserted normally insidethe bag mouth based on that detection result. Thus, detection anddecision of the hopper insertion state can be done easily.

In this method too, if it is determined that the hopper is not insertedinto the bag mouth normally, it is as described above possible to haltthe operation of the packaging means (for example, a liquid loadingdevice, bag mouth sealing device, device to transfer to a vacuumpackaging machine, etc.) at steps following the relevant bag or todischarge only the relevant bag at a discharge position different fromthe usual discharge position or to halt the entire packaging device.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic perspective view of the vicinity of the bag mouthopening step position in a bag-filling packaging machine in accordancewith the present invention;

FIG. 2(a) is a schematic perspective view of the vicinity of the itemsupply step position and FIG. 2(b) is an enlarged front view thereof;

FIG. 3 is a schematic perspective view of the vicinity of the idle stepposition after the item supply step position;

FIG. 4(a) is a schematic perspective view of the vicinity of the itemsupply step position and FIG. 4(b) is an enlarged front view thereof,showing the deformed configuration of the bag when insertion of thehopper into the bag mouth fails;

FIG. 5 is a schematic perspective view of the vicinity of the idle stepposition after the item supply step position, showing the situation wheninsertion of the hopper into the bag mouth fails and the items to bepacked spill from the lower end of the raised hopper; and

FIG. 6 is a schematic perspective view of the vicinity of the itemsupply step position in another bag-filling packaging machine inaccordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The method for detecting a hopper insertion state in accordance with thepresent invention will be described below in detail with reference toFIGS. 1 through 6.

The bag-filling packaging machine shown in FIG. 1 has a plurality (onlyone pair is shown) of gripper pairs 2, which hold the left and rightedges (or both side edges) of a bag 1 so that the bag hangs down. Thegrippers 2 are disposed at equidistant separation on the periphery of atable 3 that is rotated intermittently (the arrow indicates the rotationdirection). A single hopper 4 is provided on the table 3 for eachrespective pair of grippers 2. The table 3 is, in the course of its onerotation, repeatedly rotated and halted the same number of times as thenumber of gripper pairs 2, and the hoppers 4 are raised and lowered at apredetermined timing through the operation of a cam rail, cam roller,and slider which are not shown in the drawings.

Disposed on the periphery of the table 3 are a bag supply device, aprinting device, a bag mouth opening device, an item supply device thatsupplies items to be packed, a sealing device, a cooling sealing device,etc., so that they are provided at positions where the operations of themachine are executed. Each time the table 3 halts, the variousoperations are carried out, including supplying of a bag to the haltedgripper pair 2, printing on the surface of the supplied bag, opening ofthe bag mouth of the supplied bag, supplying of the items to be packedinto the supplied bag, sealing the bag mouth, cooling the seal area,etc. Subsequently, the product bag that contains the items is dischargedto the outside of the packaging machine.

The construction and functions of the bag-filling packaging machinedescribed above are known from, for instance, Japanese PatentApplication Laid-Open (Kokai) No. 2004-67224.

In the bag-filling packaging machine shown in FIG. 1, the raising andlowering movement of the hopper 4 begins at a bag mouth opening stepposition and ends at an appropriate timing after the step of supplyingthe items to be packed into the supplied bag. The raising and loweringmovement of the hopper 4 will be described below in more detail (seeJapanese Patent Application Laid-Open (Kokai) No. 2004-67224 in thismatter).

(1) The above-described cam rail is disposed in a ring shape centered onthe rotational axis of the table 3. As the table 3 is rotated, the camroller (fixed to each hopper 4) is rotationally moved along the camrail, and the hopper 4 is also rotationally moved.

-   -   As the table 3 is rotated, the hopper 4 leaves the printing step        position and is rotationally moved toward the bag mouth opening        step position. During this interval, the cam rail is disposed at        a high position and on a horizontal plane, so that the hopper 4        is rotationally moved on a horizontal plane at its ascended        position (which is a position a predetermined distance from the        upper end of the bag mouth); and when the table 3 is halted with        movement, it is stopped at the bag mouth opening step position.    -   At the bag mouth opening step position, the cam rail is        positioned so that it sandwiches the slider between the high        position and low position, and the cam roller leaves the cam        rail at the high position immediately before halting and being        transferred to the slider, which is standing by at the same        height. This slider is disposed at the bag mouth opening step        position, and it has an elevator function for vertically        lowering the cam roller from the high position to the low        position.

(2) The bag mouth is opened at the bag mouth opening step position; andat the same time (at the timing shown in FIG. 1), the slider descends soas to lowers the cam roller, thus allowing the hopper 4 to be lowered tothe descended position at the same time, so that the lower end of thehopper 4 is inserted into the bag mouth of the bag 1.

(3) As the table 3 is rotated, the hopper 4 at the bag mouth openingstep position is rotationally moved toward the next halt position (theitem supply step position where the item to be packed is supplied to thehopper and then into the bag). Simultaneously with the start of rotationof the table 3, the cam roller leaves the slider and is transferred tothe cam rail disposed at the low position whose height is as the same asthe slider. During this interval, since the cam rail is on a horizontalplane at the low position, the hopper 4 is rotationally moved on thehorizontal plane at the descended position and is halted at the itemsupply step position when the rotation of the table 3 is halted.

-   -   Meanwhile, the slider immediately returned to the original high        position after leaving the cam roller and waits for the next cam        roller to be transferred thereon.

(4) At the item supply step position, the items to be packed areinjected into the hopper 4, and the items pass through the hopper 4 andare loaded into the bag 1. FIG. 2(a) shows the positional relationshipbetween the hopper 4 and bag 1 at the item supply step position, and italso shows the state of items to be packed 5 being injected into thehopper 4 from an item supply device.

(5) As the table 3 is rotated, the hopper 4 at the item supply stepposition is rotationally moved toward the next halt position (an idlestep position). The cam rail slants upward from the item supply stepposition to this idle step position; and at the idle step position, itis positioned at the same high position as the printing step position.Accordingly, the bottom end of the hopper 4 is withdrawn from (or outof) the bag mouth during this rotational movement; and when the hopper 4is halted at the idle step position, the hoper 4 has arrived at theabove-described ascended position. FIG. 3 shows the positionalrelationship between the hopper 4 and bag 1 at this idle step position,and it also shows the state of items to be packed 5 loaded inside thebag 1.

(6) The cam rail is disposed horizontally at the high position from theidle step position to the printing step position. Therefore, the hopper4 is kept in the ascended position while rotationally moving throughthis interval.

In the bag-filling packaging machine shown in FIG. 1, a reflectingmirror 6 is provided on the table 3 for each gripper pair 2. Thereflecting mirror 6 is disposed parallel to the tangent direction of theround table 3 on a perpendicular plane with respect to the flat surfaceof the table 3. Also, as shown in FIG. 2(a), a pair of reflecting-typephotoelectric sensors (bag mouth detecting sensors) 7 are provided atthe above-described item supply step position so as to face thereflecting mirror 6 at the outside of the table 3; and as shown in FIG.3, a group of reflecting-type photoelectric sensors (falling itemsdetecting sensors) 8 are provided at the above-described idle stepposition so as to face the reflecting mirror 6 at the outside of thetable 3.

A detection part 9 (light passage route) of each one of thephotoelectric sensors 7 is positioned, as shown in FIG. 2(b), so that itis slightly below the upper end 1 a of the bag mouth and at the bag face(unsealed face) located between the side seal part 1 b of the bag 1 andthe hopper 4 when the lower end of the hopper 4 is inserted normallyinside the bag mouth of the bag 1. Also, as shown in FIG. 4(b), thedetection part 9 is set at a position where the bag face is removed from(or out of) the detection part 9, if the lower end of the hopper 4catches the bag mouth edge of the bag 1 so that the hopper 4 is notinserted normally into the bag mouth and the bag mouth is pressed by thelower end of the hopper 4 and takes an abnormally deformed shape (inFIG. 4(b), a part of the bag mouth edge is folded inward). In FIGS. 2(b)and 4(b), only one of two detection parts 9 which are set so as to be atboth shoulder portions of the bag is shown.

Detection by the photoelectric sensors 7 (light emission by thelight-emitting part and detection by the light-receiving part of thephotoelectric (bag mouth detecting) sensors 7) occurs for the bag 1supplied and stopped at the item supply step position immediately afterthe table 3 is halted. If the lower end of the hopper 4 is insertednormally into the bag mouth of the bag 1 as shown in FIG. 2(a), thedetection parts 9 of the photoelectric sensors 7 are positioned at thebag face of the bag 1 as shown in FIG. 2(b); and thus, light emitted bythe light-emitting parts of the photoelectric sensors 7 is blocked bythe bag face and does not reach the reflecting mirror 6; as a result, nolight is reflected by the mirror 6, and no reflected light is detectedby the light-receiving part of the sensors 7. This means that the bagmouth of the bag 1 is not abnormally deformed, and this detection resultis sent to the control device (not shown in the drawings) of thebag-filling packaging machine. The control device determines that thehopper 4 was inserted into the bag mouth without problems. The detectiontime (the time from starting detection until the detection ends) is setto be very short.

On the other hand, if the lower end of the hopper 4 catches on the bagmouth edge of the supplied bag 1 and is not inserted into the bag mouthnormally, and the bag mouth is pressed by the lower end of the hopper 4and abnormally deformed (see the part of the bag mouth irregularlydeformed as shown by dashed line in FIG. 4(a), and see the normal bagmouth shown by two dotted line A and the irregularly deformed bag mouthshown by solid line B in FIG. 4(b)), and the bag face is removed from(or out of) the detection part 9 of one or both of the photoelectricsensors 7 as shown in FIG. 4(b), light from one or both of thelight-emitting parts of the photoelectric sensors 7 reaches thereflecting mirror 6 and is reflected; as a result, the reflected lightis detected by the light-receiving part. This detection result is sentto the control device of the bag-filling packaging machine, and thecontrol device determines that insertion of the hopper 4 into the bagmouth failed.

Detection parts (light passage routes) of the photoelectric (fallingitems detecting) sensors 8 that are provided at the idle step positionare set at a number of locations in the horizontal direction in thespace between the lower end opening of the hopper 4 which is at theascended position and the upper end of the bag 1 as shown in FIG. 3.

Detection by the photoelectric sensors 8 (light emission by thelight-emitting part and detection by the light-receiving part of thephotoelectric sensors 8) is done at the above-described idle stepposition immediately after the rotation of the table 3 is halted. If allof the items to be packed that are injected into the hopper 4 are loadedinto the bag 1 while at this idle step position as shown in FIG. 3, allof the light emitted from the light-emitting parts of the photoelectricsensors 8 reaches the reflecting mirror 6 without being blocked and isreflected; as a result, the reflected light reaches the light-receivingpart of each photoelectric sensors 8 without being blocked, and eachlight-receiving part continuously detects the reflected light during theappropriately set detection time (which is set to be longer than that ofthe photoelectric sensors 7). This means that the items to be packed 5did not fall from the hopper 4; and this detection result is sent to thecontrol device of the bag-filling packaging machine, and the controldevice determines that the hopper 4 was inserted into the bag mouthnormally without problems.

On the other hand, if the lower end of the hopper 4 catches on the bagmouth edge of the bag 1 as shown in FIG. 4(a) and is not insertednormally into the bag mouth and part of the bag mouth of the bag 1 isfolded inside, then some of the items to be packed 5 remain inside thehopper 4 until the hopper 4 is completely withdrawn from the bag mouthof the bag 1. As a result, after the hopper 4 is halted at the idlestep, the items to be packed 5 may fall into the bag 1 or outside thebag 1 from the bottom end opening of the hopper 4 as shown in FIG. 5. Inthis case, light from the light-emitting part or its reflected light istemporarily blocked by the falling items at one or more than one of thephotoelectric sensors 8, so that during that detection time there is abrief moment when one or a plurality of the correspondinglight-receiving parts does not detect the reflected light. This meansthat the items to be packed 5 that remained inside the hopper 4 fell;and this detection result is sent to the control device of thebag-filling packaging machine, and the control device determines thatinsertion of the hopper 4 into the bag mouth failed.

In the above-described method for detecting the hopper insertion state,if the control device determines that the hopper 4 was inserted into thebag mouth of the bag 1 normally without problems, the packagingoperations by various packaging means (the sealing device, coolingsealing device, etc.) at subsequent steps are performed as programmed;if, however, the control device determines that insertion of the hopper4 into the bag mouth was improper and failed, then the packagingoperations by various packaging means at subsequent steps are halted forthe relevant bag 1, as described earlier, or the entire packagingmachine is halted; and if the detection result of the photoelectricsensors 7 was failure, then controls such that the items to be packedare not injected into the hopper 4 at the item supply step position,etc. are executed.

The bag-filling packaging machine described above can be modified as,for example, describe below.

(1) In the described embodiment, the photoelectric sensors 7 fordetecting deformation of the bag mouth are provided at the item supplystep position. However, they can be disposed at the bag mouth openingstep position, so that the presence or absence of deformation of the bagmouth is detected immediately after the hopper 4 arrives at thedescended position.

(2) In the foregoing embodiment, the slider is provided at the bag mouthopening step position, and the cam roller is lowered from the highposition to the low position while the table 3 is halted (the hopper 4is lowered from the ascended position to the descended position) and thelower end of the hopper 4 is inserted into the bag mouth immediatelyafter opening. However, it is also possible to make the cam railcontinuous without providing a slider and to lower the hopper 4 whilerotationally moving from the bag mouth opening step position to the nexthalt position (the item supply step position), and insert the lower endof the hopper 4 into the bag mouth.

(3) The above embodiment uses photoelectric sensors 7 and 8. However,other types of sensors can be used as long as it is possible suchsensors detect deformation of the bag mouth and falling items asdescribed above.

FIG. 6 shows another type of bag-filling packaging machine.

In the bag-filling packaging machine of FIG. 6, a plurality (only onepair is shown in the drawing) of gripper pairs 12, which hold the leftand right (or both side) edges of a bag 111 so that the bag hangs down,are provided at equidistant separation on the periphery of a table 13that is rotated intermittently; and in the course of one rotation, thetable 13 repeatedly is rotated and halted the same number of times asthe number of gripper pairs 12.

On the periphery of the table 13, a bag supply device, a printingdevice, a bag mouth opening device, a hopper 14 and its raising/loweringdevice, an item supply device that supplies items to be packed, asealing device, a cooling sealing device, etc. are provided. Each timethe table 13 halts, the various steps are carried out includingsupplying of a bag to the halted gripper pair 12, printing on the bagsurface, opening of the bag mouth, inserting of the hopper 14 into thebag mouth of the supplied bag and supplying of the items to be packedinto the bag, sealing of the bag mouth, cooling of the seal area, etc.Subsequently, the product bag is discharged to the outside of thepackaging machine.

The bag-filling packaging machine shown in FIG. 6 is an ordinaryrotary-type bag-filling packaging machine, and its construction andfunctions are conventionally known.

In the bag-filling packaging machine shown in FIG. 6, the hopper 14 andits raising/lowering device are disposed at the item supply stepposition together with the item supply device, and the hopper 14 israised and lowered at this item supply step position as described below.

(1) The bag 11 with its bag mouth opened by the bag mouth opening deviceat the bag mouth opening step position is halted at the item supply stepposition due to the intermittent rotation of the table 13. At this time,the hopper 14 is at its ascended position (a position at a predetermineddistance from the upper end of the bag mouth) at the item supply stepposition.

(2) Immediately after the table 13 is halted, the hopper 14 is loweredto the descended position by the raising/lowering device, and the lowerend of the hopper 14 is inserted into the bag mouth of the bag 11, andthen the items to be packed are injected into the hopper 14 and passthrough the hopper 14 so as to be loaded into the bag 11.

(3) The hopper 14 returns is raised to the ascended position, then thetable 13 is rotated, so that the loaded bag 11 with the items is movedto the next step position (sealing step position).

In this bag-filling packaging machine shown in FIG. 6, a reflectingmirror 16 is provided on the table 13 for each gripper pair 12. Thereflecting mirror 16 is parallel to the tangent direction of the roundtable 13 on a perpendicular plane with respect to the flat surface ofthe table 13. In addition, a pair of reflecting-type photoelectricsensors (bag mouth detecting sensors) 17 and a group of reflecting-typephotoelectric sensors (falling items detecting sensors) 18 are providedso as to face the reflecting mirror 16 at the outside of the table 13 atthe above-described item supply step position.

The detection part (light passage route) of the photoelectric (bag mouthdetecting) sensors 17 is set to be at essentially the same position asthe detection part 9 in the bag-filling packaging machine shown in FIGS.1 to 5. In other words, the detection part (light passage route) of thephotoelectric sensors 17 is set at a position where abnormal deformationof a bag can be detected as required. Also, the detection parts of thephotoelectric (falling items detecting) sensors 18 too are essentiallythe same as the detection parts in the bag-filling packaging machineshown in FIGS. 1 to 5. In other words, the detection parts of thephotoelectric sensors 18 are set at a number of locations in thehorizontal direction in the space between the lower end opening of thehopper 14 which is at the ascended position and the upper end of the bag11.

Detection by the photoelectric sensors 17 occurs immediately after thehopper 14 reaches its descended position. Also, detection by thephotoelectric sensors 18 starts at the moment when the items to bepacked have been injected into the hopper 14 by the supply device andraising of the hopper 14 starts and its lower end opening tip passes theposition of the detection part of the photoelectric sensors 18. Asdescribed previously, the detection time of the photoelectric sensors 17(time from starting detection until the detection ends) is very brief,but the detection time of the photoelectric sensors 18 is preferably setsomewhat longer than that of the photoelectric sensors 17 to take intoaccount the timing of the falling of the items to be packed.

The photoelectric sensors 17 and 18 have exactly the same function asthe photoelectric sensors 7 and 8 described above. Their detectionresult is sent to the control device of the bag-filling packagingmachine, and the control device determines whether the insertion of thehopper 14 into the bag mouth is good or bad (or acceptable or not) onthe same standard as that of the control device for the bag-fillingpackaging machine explained in FIG. 1. The control method too after thedecision is the same as that of the control device for the bag-fillingpackaging machine explained in FIG. 1, and further detailed explanationthereof is omitted.

1. A method for detecting a hopper insertion state for a bag-fillingpackaging machine that opens a bag mouth of a supplied bag, inserts ahopper into the bag mouth of the supplied bag, loads items to be packedinto the bag via said hopper, and then withdraws said hopper from thebag mouth, said method comprising the steps of: detecting deformation ofthe bag mouth during insertion operation of said hopper into the bagmouth by bag mouth detecting sensors provided in said bag-fillingpackaging machine, and determining whether or not a hopper insertionstate in the bag mouth is acceptable based on a detection result of saidbag mouth detecting sensors.
 2. The method for detecting a hopperinsertion state according to claim 1, wherein in said bag-fillingpackaging machine, both edges of the supplied bag are held by grippersso that the supplied bag is kept hanging down.
 3. The method fordetecting a hopper insertion state according to claim 2, furthercomprising the steps of detecting whether or not items to be packed arefalling from said hopper when the hopper is withdrawn from the bag mouthby falling items detecting sensors provided in said bag-fillingpackaging machine, and determining whether or not the hopper insertionstate in the bag mouth is acceptable based on a detection result of saidfalling items detecting sensors.
 4. A method for detecting a hopperinsertion state for a bag-filling packaging machine that: holds bothedges of a supplied bag by grippers, thus keeping the supplied baghanging down, opens the bag mouth of the supplied bag, inserts a hopperinto the bag mouth, loads items to be packed into the bag via saidhopper, and then withdraws said hopper from the bag mouth; wherein saidmethod comprises the steps of: detecting items to be packed falling fromthe hopper when said hopper is withdrawn from the bag mouth by fallingitems detecting sensors, and determining whether or not the hopperinsertion state in the bag mouth is acceptable based on a detectionresult of said falling items detecting sensors.
 5. The method fordetecting a hopper insertion state according to any one of claims 2through 4, wherein said bag-filling packaging machine comprises: anintermittently rotating table, a plurality of pairs of grippers forholding both side edges of a bag so that the bag hangs down, saidplurality of pairs of grippers being disposed at equidistant separationon a periphery of said intermittently rotating table, and a hopper thatis raised and lowered at a predetermined timing and is disposed on saidtable so as to correspond to each respective gripper pair; and whereinvarious packaging means including a bag supply device, a bag mouthopening device, an item supply device, a sealing device are disposed onthe periphery of said table; and various packaging operations includingsupplying of a bag, opening of the bag mouth, inserting of the hopperinto the bag mouth, loading of the items to be packed in to the bag,withdrawing of the hopper from the bag mouth, sealing of the bag mouthare performed when said table is rotated once.